Windows makes it surprisingly easy to work with multiple monitors, but in most cases you’ll be working with two, or perhaps three at a push. Two is great for having several applications visible at once, while three is great for gaming – if your graphics card is up to the job. You might occasionally connect a projector to your laptop, but as Windows sees this as just another monitor, the process is exactly the same.
How to duplicate the screen in Windows
When you first connect a second monitor, Windows should detect it and automatically shows the screen on both displays. This is the case regardless of whether you have a PC with two monitors or a laptop with a screen or projector attached.
If you don’t see an image on the second screen, look for a function key on the top row of keys on your laptop which shows two monitors. Press the Fn key and the appropriate function key (F5 on the laptop below, for example) and it should toggle through the various configurations: laptop display only, laptop + external screen, external screen only.
You can also try pressing the Windows key and P at the same time for the same effect.
If you still have no image and your second screen is displaying "No signal" then try selecting a different input as it might not automatically select the one you're using. You'll have to check your monitor or projector's manual to find out how to do that if it's not obvious from the available buttons and menus.
If all else fails, go to the Windows desktop, right click and choose Screen resolution (Display settings in later versions including Windows 10). If you see only one screen in the drop-down Display list, try clicking the Detect button to force Windows to scan for the second screen. In Windows 10, scroll down until you see Multiple Displays and click the Detect button.
How to configure multiple screens in Windows
When all screens are detected, you can choose how Windows uses them.
If you want to duplicate the screens and have the same image on both, make sure ‘Duplicate these displays’ is selected in the Multiple displays drop-down menu. It's much the same in Windows 8 and 10.
In Windows 10, you won't see the Resolution setting. This has been moved to 'Advanced' so you have to click 'Advanced display settings' to see the drop-down menu.
It's worth noting that duplicating displays is often a compromise if your screens have different resolutions or aspect ratios. For example, if you hook up a 1024x768 projector to a laptop with a1366x768 screen, both will run at 1024x768, and you’ll end up with black bars on the left and right on your laptop screen.
How to extend the desktop across multiple monitors
If you’re not using a projector, which is when it makes most sense to duplicate the screen, then you probably want to extend the desktop to have different things on each screen.
To do that, simply choose ‘Extend these displays’ instead of ‘Duplicate these displays’.
You can select a monitor in the diagram at the top and drag it to the position it’s in on your desk. Here we’ve put the second monitor on the left of the laptop because it defaults to the right. You can move the smaller screen up and down, too. This affects where your mouse cursor can cross the screens.
You’ll also notice you can select different resolutions for each screen, but you much select each screen in turn. Only one of the monitors can be your main monitor, but it doesn't matter which: you choose by clicking on the screen in the diagram and then checking the box next to 'Make this my main screen'.
In Windows 7, that means it will be the only monitor with a task bar and start button. In Windows 8 and 10, you get those on all screens, but only the notification area and clock on the main screen.